The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingInspection
Inspect starter assembly
Notice:
These tests must be performed within 3 to 5 seconds
to avoid burning out the coil.
Perform the pull-in test.
Disconnect the lead wire from terminal c.
Connect the battery to the magnetic switch as
shown in the illustration. Check that the clutch ...
On-vehicle inspection
Check steering pad assembly (vehicle not involved in collision and
airbag not deployed)
Perform a diagnostic system check (see page rs-
49).
With the steering pad (with airbag) installed on the
vehicle, perform a visual check:
check for cuts, cracks or discoloration on the
...
Battery temperature sensor circuit
Description
The battery temperature sensor installed on the battery current sensor
detects battery temperature.
A thermistor is integrated into the battery temperature sensor, and the
resistance in the battery
temperature sensor changes according to the battery temperature.
The r ...